U.S. patent application number 10/620783 was filed with the patent office on 2004-01-22 for method for preparing the reactive tinting compound and the tinted contact lens.
Invention is credited to Hong, Shinn-Gwo.
Application Number | 20040012757 10/620783 |
Document ID | / |
Family ID | 30442118 |
Filed Date | 2004-01-22 |
United States Patent
Application |
20040012757 |
Kind Code |
A1 |
Hong, Shinn-Gwo |
January 22, 2004 |
Method for preparing the reactive tinting compound and the tinted
contact lens
Abstract
A method for preparing the tinted contact lens with the
covalently bonded novel reactive tinting compound is disclosed. The
reactive tinting compound with mono vinyl functionality is prepared
by reacting the reactive dye with a hydrophilic monomer containing
both pendent hydroxyl and vinyl groups under an alkaline condition.
The water soluble reactive dyes containing either
difluoro-chloropyrimidine or .beta.-sulphatoethylsulphone reactive
groups are used for synthesis of the reactive tinting dye. The lens
forming materials is photo-polymerized in the presence of the
reactive tinting compound to prepare a tinted contact lens. The
reactive tinting compound is copolymerized with the lens forming
monomers in a single photo-polymerization step that required no
subsequently alkaline soaking or developing step as used in the
prior art. In addition, the covalently bonded dye is stable and
durable in the lens and does not fade or leach out after multiple
high-pressure thermal sterilization.
Inventors: |
Hong, Shinn-Gwo; (Chungli
City, TW) |
Correspondence
Address: |
Supreme Patent Services
Post Office Box 2339
Saratoga
CA
95070-0339
US
|
Family ID: |
30442118 |
Appl. No.: |
10/620783 |
Filed: |
July 15, 2003 |
Current U.S.
Class: |
351/159.32 ;
351/159.66; 351/159.74 |
Current CPC
Class: |
G02B 1/043 20130101;
D06P 1/0064 20130101; C08F 246/00 20130101; D06P 1/008 20130101;
C09B 69/10 20130101 |
Class at
Publication: |
351/162 |
International
Class: |
G02C 007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 16, 2002 |
TW |
91115819 |
Claims
What is claimed is:
1. A method for preparing a reactive tinting compound for tinted
contact lens comprising the step of: (a) carrying out a reaction of
a first compound with a second compound to generate a product of
reactive tinting compound, wherein the first compound is a
hydrophilic compound with pendant hydroxyl and unsaturated vinyl
groups, and the second compound is a radiation-absorbing and water
soluble dye with substituted fluoro-chloropyrimidine or
.beta.-sulphatoethylsulphone reactive group; and (b) recovering the
product after the reaction is completed.
2. The method according to claim 1, wherein the molar ratio of the
first compound to the second compound is 1/1 to 5/1.
3. The method according to claim 1, wherein the first compound is
selected from a group consisting of 2-hydroxyethyl methacrylate,
hydroxylethyl acrylate, and glycerol methacrylate.
4. The method according to claim 1, wherein the second compound
with substituted difluoro-chloropyrimidine reactive group is C.I.
Reactive Blue 114.
5. The method according to claim 1, wherein the second compound
with substituted .beta.-sulphatoethylsulphone reactive group is
selected from a group consisting of C. I. Reactive Yellow 15, C. I.
Reactive Red 180, C. I. Reactive Blue 19, and C. I. Reactive Blue
21.
6. The method according to claim 1, wherein step (a) comprises the
steps of: (i) preparing a mixture of the first compound, a base
compound, and a polymerization inhibitor in water; (ii) mixing the
second compound with the mixture of step (i); and (iii) initiating
a synthesis reaction of the reactive tinting compound under
heating.
7. The method according to claim 6, wherein the molar ratio of the
first compound to the second compound is 1/1 to 5/1.
8. The method according to claim 6, wherein the first compound is
selected from a group consisting of 2-hydroxyethyl methacrylate,
hydroxylethyl acrylate, and glycerol methacrylate.
9. The method according to claim 6, wherein the second compound is
C. I. Reactive Blue 114 (RB 114).
10. The method according to claim 6, wherein the base compound is
selected from a group consisting of ammonia, alkaline metal
hydroxide, and salt of alkaline metal.
11. The method according to claim 6, wherein the molar ratio of the
base compound to the second compound is 1/1 to 5/1.
12. The method according to claim 6, wherein the polymerization
inhibitor is selected from a group consisting of hydroquinone,
methyl hydroquinone, hydroquinone monomethyl ether, catechol and
pyrogallol.
13. The method according to claim 6, wherein the polymerization
inhibitor is 0.02 to 3% based on the weight of the first
compound.
14. The method according to claim 6, wherein the reaction is at 50
to 100.degree. C.
15. The method according to claim 6, wherein the reaction is for 12
to 24 hours.
16. The method according to claim 1, step (a) comprises the steps
of i) activating the second compound with a base compound in water,
ii) mixing the first compound with the resulting mixture of step
i); iii) optionally mixing a polymerization inhibitor with the
mixture of step ii); and iv) initiating a synthesis reaction of the
reactive tinting compound.
17. The method according to claim 16, wherein the activating step
is at 30 to 80.degree. C.
18. The method according to claim 16, wherein the activating step
is for 0.5 to 4 hours.
19. The method according to claim 16, wherein the molar ratio of
the first compound to the second compound is 1/1 to 5/1.
20. The method according to claim 16, wherein the first compound is
selected from a group consisting of 2-hydroxyethyl methacrylate,
hydroxylethyl acrylate, and glycerol methacrylate.
21. The method according to claim 16, wherein the second compound
is selected from a group consisting of C. I. Reactive Yellow 15, C.
I. Reactive Red 180, C. I. Reactive Blue 19, and C. I. Reactive
Blue 21.
22. The method according to claim 16, wherein the base compound is
selected from a group consisting of ammonia, alkaline metal
hydroxide and salt of alkaline metal.
23. The method according to claim 16, wherein the molar ratio of
the base compound to the second compound is 1/1 to 5/1.
24. The method according to claim 16, wherein the polymerization
inhibitor is selected from a group consisting of hydroquinone,
methyl hydroquinone, hydroquinone monomethyl ether, catechol and
pyrogallol.
25. The method according to claim 16, wherein the polymerization
inhibitor is 0.02 to 3% based on the weight of the first
compound.
26. The method according to claim 16, wherein the reaction is at
room temperature to 50.degree. C.
27. The method according to claim 16, wherein the reaction is for
12 to 24 hours.
28. A reactive tinting compound which is prepared by the steps
comprising (1) carrying out a reaction of a first compound with a
second compound to generate a product of reactive tinting compound,
wherein the first compound is a hydrophilic compound with pendant
hydroxyl and unsaturated vinyl groups, and the second compound is a
radiation-absorbing and water soluble dye with substituted
fluoro-chloropyrimidine or .beta.-sulphatoethylsulphone reactive
group; and (2) recovering the reactive tinting compound after the
reaction is completed.
29. A tinted contact lens comprising a hydrophilic monomer
material, an inert diluent, an acrylic crosslinker with multiple
unsaturated vinyl groups and a reactive tinting compound which is
prepared by the steps comprising a. carrying out a reaction of a
first compound with a second compound to generate a product of
reactive tinting compound, wherein the first compound is a
hydrophilic compound with pendant hydroxyl and unsaturated vinyl
groups, and the second compound is a radiation-absorbing and water
soluble dye with substituted fluoro-chloropyrimidine or
.beta.-sulphatoethylsulphone reactive group; and b. recovering the
product after the reaction is completed.
30. The lens of claim 29 wherein the amount of the reactive tinting
compound is 0.01 to 0.25% based on the weight of the hydrophilic
monomer material.
31. The lens of claim 29 wherein the hydrophilic monomer material
comprises hydroxy ethyl methacrylate, methacrylic acid, and N-vinyl
pyrrolidone.
32. The lens of claim 29 wherein the acrylic crosslinker with
multiple unsaturated vinyl groups is selected from a group
consisting of ethylene glycol dimethacrylate and trimethylolpropane
trimethacryalte.
Description
[0001]
1TABLE 1 Selected Properties of Prepared Tinted Contact Lens The
Reactive Lens Tinting Water Diam- Tensile Compound Content eter
Strength Elongation Tinting Added (%) (mm).sup.# (Kg/cm.sup.2)* (%)
Stability.sup.+ Example 1 .sup. 54.4 (0.8).sup.$ 14.0 2.2 123 .+-.
11 Stable Example 2 55.1 (0.9) 14.1 2.1 120 .congruent. 12 Stable
Example 3 54.6 (0.8) 14.0 2.2 118 .+-. 10 Stable Example 4 54.8
(0.7) 14.0 2.1 121 .+-. 13 Stable Example 5 54.3 (0.9) 14.1 2.1 122
.+-. 12 -Stable Control 55.2(0.7) 14.1 2.2 126 .+-. 11 (no dye)
.sup.$( ): standard deviation. .sup.#99% confidence interval of
lens diameter is less than .+-. 0.2 mm *standard deviation of
tensile strength is less than 0.2 Kg/cm.sup.2 .sup.+Stable: tinting
color is not faded or migrated after cyclic autoclave aging.
-Stable: a small noticeable fading after cyclic autoclave
aging.
BACKGROUND OF THE INVENON
[0002] 1. Field of the Invention
[0003] The present invention relates to a process for preparing a
reactive tinting compound and the use of such a compound to
manufacture the tinted soft contact lenses. More particularly, the
invention relates to a tinted hydrophilic soft contact lens
containing covalently bonded dye that does not leach out and fade
after multiple autoclave sterilization.
[0004] 2. The Prior Arts
[0005] Many different processes have been disclosed to produce
tinted or color ophthalmic lenses, such as contact lenses, for
various functional purposes. For example, the tinted lens not only
can serve the purpose of changing the apparent color or the iris of
the wearer but also offer the lenses to be easily located in the
clear solution within the lens storage, disinfecting, or cleaning
container.
[0006] Usually, the tinting dye can be imparted to the lens either
before or after the lens forming materials are polymerized. A
conventional method to impart color to the contact lens is to
dissolve or disperse the inorganic pigment or the long chain
organic dye in the monomer precursor or in the polymer matrix
before the lens is formed. The inorganic pigment or the long chain
organic dye is entrapped in the lens to give the desirable color.
However, this method is inadequate for coloring the hydrophilic
soft contact lens because the great water content in the lens
usually induces a migration or leaching of the colorant. This
undesirable migration or leaching can be accelerated during the
high-pressure heat sterilization treatment as commonly applied with
the hydrophilic soft lens.
[0007] The use of a water insoluble dye in the soft lens to
alleviate the aforementioned shortage is proposed in U.S. Pat. No.
4,252,421. The tinted lens is prepared by heat curing hydrophilic
lens forming monomers with the presence of the water insoluble
phthalocyanine dye such as the copper phthalocyanine. The
phthalocyanine dye is entrapped in the finished lens and believed
to be stable at a maximal hydration content of 35.7%.
Unfortunately, this water insoluble phthalocyanine dye still can
leach out of the lens with the use of the hydroxyethyl methacrylate
(HEMA) as the hydrophilic comonomer and with a water content of
40%. Moreover, the leaching problem may worsen with greater water
content.
[0008] The use of copper phthalocyanine pigment (Color Index
Pigment Blue 15) to prepare a tinted contact lens is also disclosed
in U.S. Pat. No. 6,149,842. The copper phthalocyanine pigment is
firstly dispersed in an aqueous solution containing the polyvinyl
alcohol (PVA) as a dispersing agent, and then mixed with the
crosslinkable PVA precursor and subsequently photopolymerized in
the mold to form the lens. No detail in performance of this dye in
the as-formed lens is disclosed. As described previously, the
leaching occurred at large water content is a potential
problem.
[0009] A similar concept is disclosed in U.S. Pat. No. 5,516,467 in
which a vat dye (for example, C. I. Vat Blue 6) is converted to a
leuco compound and dissolved in the hydrophilic NN-dimethyl
acrylamide monomer to prepare a tinted monomer solution. Then this
solution is polymerized with other constituents under heat to form
the lens and subsequently boiled to convert the solubilized leuco
compound into an insoluble vat dye. Although the vat dye is not
covalently bonded with the lens forming materials, it is reported
to have a great stability and does not fade after 200 hours in the
boiling water. However, the fixed vat dye may again be converted to
the soluble leuco compound under a suitable alkaline condition and
be unevenly reacted under an acid environment.
[0010] The other method for imparting color to a contact lens is to
coat the finished lens by printing or transfer printing method.
Basically, this method usually applies coloring ink containing
solvent-based colorant to the lens with a silicone rubber pad. The
transferring method is questionable because it could not give an
unblemished, solid covering of colorant on the dry lens surface.
Many attempts have been suggested to solve this problem. Some
propose to use multiple transfer printing steps to coat mottled
color dots onto the lens surface. Some apply pigment/monomer
suspension to the mold that stamped or printed with specific
geometries and spacing, and then form the tined lens with the
conventional spin casting technique as disclosed in U.S. Pat. No.
4,640,805. Despite the ease of the blemish defect, all these
modified methods suffer the potential risk of colorant migration
during autoclave sterilization because of using the non-covalently
bonded dyes. As a result, the reactive tinting dye that can be
copolymerized with lens materials is preferred to prevent leaching
of the dye from the lenses during various service environments.
[0011] A reactive dye used for preparing the transfer printing ink
to remedy the previous migration shortage is disclosed in U.S. Pat.
No. 5,352,245. The patent proposes using a reactive dye, e.g.,
Ramazol Black B, together with the polyvinylpyrolidone binder and a
non-ionic surfactant to prepare the ink and then transfer printing
it onto the hydrophilic contact lens to form the tinted lens with
the desired pattern. The reactive dye is supposed to be covalently
bonded with the lens materials after subsequent immersion in the
basic solution. Yet no performance detail of the tined lens is
disclosed. In addition, the method is tedious and has the shortage
similar to that present in the soaking-to-fix techniques.
[0012] Many patents include U.S. Pat. Nos. 4,559,059, 4,468,229,
4,157,892, 4,891,046, 4,553,975, 4,929,250, 5,292,350, and 5480927
propose the lens tinting method by soaking the formed lens together
with the reactive dye in the alkaline solution to chemically bond
the dyes with the lens materials. The reactive tinting dye can
either be premixed with the monomer mixtures before the
polymerization step or be added to the basic solution after the
lens is polymerized. Regardless different reactive dyes and
procedures proposed in these patents, they are usually
time-consuming and require multiple steps, such as neutralization,
extraction, and rinsing steps to tint the lens. Additionally, the
processing variables should be carefully controlled to prevent
uneven dispersion and colorization.
[0013] A more promising method to add the desirable color to the
lens is to covalently bond the monomer or prepolymer with the
reactive dye first and then introduce this functionalized precursor
to the mold and cure. This technique will greatly alleviate the
processing problems described in soaking-to-fix methods. A few of
patents, for example, U.S. Pat. Nos. 4,252,421, 5,944,853,
5,938,795, 5,871,675, 6,149,692, 4,795,794, and 6,162,844, use the
aforementioned technique to chemically fix the dye with the lens
forming materials before the polymerization step. The differences
among these patents are mainly on types of reactive dye and
precursor reacted. Although advantages are obtained in these
patents, some patents still have problems such as the low yield and
tedious purification step. For example, a vinyl-sulfone type
reactive dye (C. I. Reactive Black 5) that reacted with the
hydroxyethyl methacrylate to prepare the dye-monomer compound with
no activating step used is disclosed in U.S. Pat. No. 5,944,853 but
a very low yield is obtained. This dye-monomer compound is not used
to prepare the soft contact lens as described in U.S. Pat. No.
5,938,795 from the same inventors of U.S. Pat. No. 5,944,853.
[0014] In summary, the previous patents disclosed for the
production of tinted contact lenses usually suffer one or more
undesired nature such as long processing time, low degree of
conversion, leaching of weakly bonded dye, fading, inconsistent
shade of the tinted lens, and tedious reacting or purification
process. Henceforth, there exists a need for preparing the tinted
contact lens with a great color fastness but without aforementioned
shortages.
SUMMARY OF THE INVENTION
[0015] A primary object of the present invention is to provide an
easy process to prepare a mono-functional reactive tinting compound
with high purity and reactivity.
[0016] The other object of the present invention is to provide an
efficient and simplified process for preparing tinted soft contact
lenses and in which a reactive tinting compound containing
mono-unsaturated vinyl group is covalently bonded to the lens
materials through a polymerization process. The as-formed tinted
lenses thus require no further rinsing step to remove residual dye
or impurities from the lenses after curing the invented reactive
tinting compound and lens forming monomers in the mold to form the
tinted lenses.
[0017] Another object of the present invention is to provide an
improved method to incorporate reactive coloring agent into a lens
that has a great color fastness and does not leach or degrade after
multiple autoclave sterilization. This outstanding durability is
resulted from the property that the invented reactive tinting
compound is capable of covalently bonding with the lens forming
materials during cure and has a great thermal stability in the
polymeric backbones.
[0018] A further object of the present invention is to provide an
efficient method to color contact lens without any subsequent dying
or developing procedures. In the present invention, the dye is
chemically fixed on the monomer to form a reactive dye-monomer
compound prior to polymerization with other hydrophilic monomers to
form the lens. As a result, the lens does not need to be immersed
in the alkaline solution or in the dye containing aqueous solution
to develop a color after the lens is formed. Additionally, neither
subsequent activation nor extraction step is required for the
as-formed lens.
[0019] The method for preparing a reactive tinting compound
comprises the steps of carrying out a reaction of a first compound
(monomer) with a second compound to generate a product of reactive
tinting compound, wherein the first compound is a hydrophilic
compound with pendant hydroxyl and unsaturated vinyl groups, and
the second compound is a radiation-absorbing and water soluble dye
with substituted fluoro-chloropyrimidine or
.beta.-sulphatoethylsulphone reactive group; and recovering the
product of reactive tinting compound after the reaction is
completed. The reactive tinting compound of the present invention
can be represented by a formula of AB, wherein A is a hydrophilic
compound with pendant hydroxyl and unsaturated vinyl groups, and B
is a radiation-absorbing and water soluble dye originally with
difluoro-chloropyrimidine or .beta.-sulphatoethylsulphone reactive
group.
DETAILED DESCRIPTON OF THE PREFERRED EMBODIMENT
[0020] The present invention is mainly applicable to tint soft
contact lenses, both corrective and noncorrective. The invention
includes synthesis of the reactive tinting compound by a simple
procedure. The invention also includes a process for preparing
tinted soft contact lenses with a great color fastness by
incorporating a reactive tinting compound in the lens forming
materials prior to polymerization.
[0021] The reactive tinting compound contains a color absorbing
moiety and one unsaturated reactive vinyl group. Through the
reactive vinyl group, the reactive tinting compound can be
covalently bonded with the lens forming materials.
[0022] The method for preparing a reactive tinting compound
comprises the steps of carrying out a reaction of a first compound
with a second compound to generate a product of reactive tinting
compound, wherein the first compound is a hydrophilic compound with
pendant hydroxyl and unsaturated vinyl groups, and the second
compound is a radiation-absorbing and water soluble dye with
substituted fluoro-chloropyrimidine or .beta.-sulphatoethylsulphone
reactive group; and recovering the product of reactive tinting
compound after the reaction is completed.
[0023] The first compound which is a hydrophilic vinylic monomer
containing hydroxyl or amine group is reacted with the second dye
compound to prepare the reactive tinting compound with one reactive
vinyl group. The preferred first compound is a comonomer used to
prepared hydrophilic soft contact lens and may be 2-hydroxyethyl
methacrylate (HEMA), hydroxylethyl acrylate, methacrylamide,
acrylic acid, vinyl pyridine, N-vinylpyrrolidone, glycerol
methacrylate and the like.
[0024] The second compound may be commercially available or can be
prepared by the conventional techniques known in the field of
organic synthesis. The preferred second compound of commercial
reactive dyes includes different types of substituted
fluoro-chloropyrimidines containing water soluble sulfonate groups.
These reactive dye reactants include, but not limited to, Color
Index (C. I.) Reactive Orange 62, C. I. Reactive Orange 64, C. I.
Reactive Red 118, C. I. Reactive Red 119, C. I. Reactive Red 123,
C. I. Reactive Red 200, C. I. Reactive Red 201, C. I. Reactive Red
F-3B, C. I. Reactive Scarlet F-2G, C. I. Reactive Blue 103 (RB103),
C. I. Reactive Blue 104, and C. I. Reactive Blue 114 (RB 114).
[0025] The preferred second compound of commercial reactive dyes
also includes different types of .beta.-sulphatoethylsulphone
derivatives containing water soluble sulfonate groups. Examples of
these reactive dyes include, but not limited to, C. I. Reactive
Yellow 14, C. I. Reactive Yellow 15, C. I. Reactive Yellow 17, C.
I. Reactive Orange 7, C. I. Reactive Orange 16, C. I. Reactive
Orange 72, C. I. Reactive Red 23, C. I. Reactive Red 49, C. I.
Reactive Red 180, C. I. Reactive Blue 19 (RB 19), C. I. Reactive
Blue 20, and C. I. Reactive Blue 21 (RB 21).
[0026] It is important that the first compound (hydrophilic vinylic
compound) and the second compound (reactive dye) should be well
dissolved in the water. These two reactants should form a
homogeneous aqueous solution before and after the reaction. Most
importantly, the resulting reactive tinting compound should be
completely miscible in the lens forming materials before and after
cure to prevent the lens defects such as uneven shade of color or
inconsistent tinting color from batch to batch.
[0027] In synthesis of the present reactive tinting compound, the
conditions can be modified according to the type of the reactants.
Although many dying assistant chemicals, such as dispersant, salt,
wetting agent, fixing agent, etc., are usually applied in the dying
process, these dying helpers are not required in the present
invention. The actual conditions chosen to react dye with the
hydrophilic vinylic reactant should be better determined
empirically and varied case by case.
[0028] (A) Preparing the Reactive Tinting Compound Using a Dye with
Difluoro-Chloropyrimidine Group
[0029] In order to promote the reaction of the
difluoro-chloropyrimidine in the dye with the hydroxyl group in the
hydrophilic vinylic monomer, it is needed to use a base such as,
for example, ammonia, triethyl amine, alkaline metal hydroxide (as
sodium hydroxide), and salt of alkaline metal (as sodium
bicarbonate) to neutralize the acid by-product. It is also
appropriate to choose a base capable of forming easily removable
by-product to facilitate the removal of neutralized salt after the
reaction. The molar amount of the base is added preferably greater
than that of the dye to improve the efficiency and yield of the
reaction. Usually, molar ratio of the base to the dye is preferably
between 1:1 to 5:1. However, the actual amount of the base used is
highly related to the strength of the base.
[0030] In the reaction, one molecule of the first compound is
bonded to one molecule of the second compound by reacting the
hydroxyl group on the first compound with the chloropyrimidine on
the second compound. Henceforth, the molar ratio of the first
compound to the second compound is preferably between 1:1 to 5:1 to
facilitate the efficiency and the completion of the reaction. The
first compound is mostly added in excess to ensure the minimal
amount of the unreacted second compound present after the reaction
is completed.
[0031] To prevent the unwanted premature reaction of the vinyl
groups during the synthesis, the use of a polymerization inhibitor
is also necessary. The inhibitor may be hydroquinone, methyl
hydroquinone, hydroquinone monomethyl ether, catechol, or
pyrogallol. The amount of a polymerization inhibitor used in the
reaction is in the range of 0.02 to 3% by weight, based on the
weight of the first compound.
[0032] In conducting the synthesis, it is important to dissolve the
maximal amounts of the first compound and the second compound in
water to increase the yield and facilitate the removal of the
unwanted by-product after the reaction. The aqueous solution of two
reactants is added with desirable amounts of base and inhibitor and
sealed in a bottle full with the nitrogen gas. The synthesis is
performed at a temperature preferably in the range of 50 to
100.degree. C. for a time preferably in the range of 12 to 24
hours. This process will lead to a considerable yield of the
product as determined by using high performance liquid
chromatography (HPLC) analyses. Of course, the temperature and the
time applied during the synthesis are dependent on the reactants
used to prepare the reactive tinting compound.
[0033] (B) Preparing the Reactive Tinting Compound Using a Dye with
.beta.-Sulphatoethylsulphone Group
[0034] In order to promote the reaction of the
.beta.-sulphatoethylsulphon- e group in the dye with the hydroxyl
group in the hydrophilic vinylic monomer, it is needed to use a
base such as, for example, ammonia, triethyl amine, and alkaline
metal hydroxide (as sodium hydroxide) to activate the
.beta.-sulphatoethylsulphone group into reactive vinyl sulfone
group first. The molar amount of the base is added preferably
greater than that of the second compound to improve the efficiency
of the activation step. Usually, the molar ratio of the base to the
second compound is preferably between 1:1 to 5:1. However, the
actual amount of the base used is highly related to the strength of
the base.
[0035] In the synthesis, one molecule of the first compound is
bonded to one molecule of the second compound by reacting the
hydroxyl group on the first compound with the activated vinyl
sulfone group on the second compound. Henceforth, the molar ratio
of the first compound to the second compound is preferably between
1:1 to 5:1 to facilitate the efficiency and the completion of the
reaction. The first compound is usually added in excess to ensure
the minimal amount of the unreacted second compound present after
the reaction is completed.
[0036] To prevent the unwanted premature reaction of the vinyl
groups during the synthesis, the use of a polymerization inhibitor
is optional. The inhibitor can be hydroquinone, methyl
hydroquinone, hydroquinone monomethyl ether, catechol, or
pyrogallol. The amount of a polymerization inhibitor used in the
reaction is in the range of 0.02 to 3% by weight, based on the
weight of the first compound.
[0037] In conducting the synthesis, the second compound is first
activated in the aqueous solution by using a desirable amount of
base. The activation step is performed at a temperature preferably
in the range of 30 to 80.degree. C. for a time preferably in the
range of 05 to 4 hours. Then the first compound and inhibitor are
added with desirable amounts to the activated second compound
solution and sealed in the bottle full with the nitrogen gas. The
synthesis is performed at the room temperature to 50.degree. C. for
a time preferably in the range of 12 to 24 hours. This process will
lead to a considerable yield of the product as determined by HPLC.
Of course, the temperature and the time applied during the
synthesis are also dependent on the reactants used to prepare the
reactive dye-monomer compound.
[0038] Upon completion of the synthesis described above for two
different types of reactive second compound, the unwanted
by-products, unreacted reactants, and water can be easily removed
from the produced reactive tinting compound by the conventional
methods such as decanting, extracting, centrifuging, and filtering.
The as-prepared reactive tinting compound has a purity greater than
85% according to the analyses of HPLC after cyclic separation by
aforementioned methods. The synthesized compound with the purity
greater than 80% can be used with the lens forming materials to
manufacture soft contact lenses without any further purification.
The impurity can be rinsed off after the lens is polymerized and
demolded. The amount of the invented reactive tinting compound
added in the lens is dependent on the lens formulation; the
required tone and color, preferably in the range of 0.01 to 0.25%,
based on the weight of the lens forming monomers. The reactive
tinting compound is completely soluble in the lens forming monomer
like the hydroxyethylmethacrylate (HEMA). The substituted vinyl
groups in the reactive tinting compound can react with the vinyl
groups in the lens forming materials and form covalent bonds
through photo initiated free radical polymerization. As a result,
the soft contact lenses formed using the reactive tinting compound
of the present invention can have the great stability during
repeated test in autoclave.
[0039] Having been fully described the present invention, examples
illustrating its practice are set forth below. These examples
should not, however, be considered to limit the scope of the
invention, which is defined by the appended claims.
EXAMPLE 1
Synthesis of the Reactive Dye RB 114
[0040] A mixture of 20 g HEMA, 4 g sodium hydroxide, 0.1 g
hydroquinone, and 500 g distilled water is well mixed in a one
liter round bottom flask for 15 minutes. Then 20 g RB114 is added
to the solution and fully dispersed in an ultrasonic bath. The
solution is stirred and reacted in an oil bath at 60.degree. C. for
24 hours. Then the solution is subsequently neutralized to about pH
7.0 with a dilute aqueous solution of HCl after the reaction. After
cooled to room temperature, the products are vacuum dried first and
then repeatedly purified three times with the methods such as
extraction with 95% ethanol, filtration, and vacuum drying. The
product after this synthesis yields about 9 g dark powders. The
result of HPLC analysis indicates that the purified product has the
purity near 98%.
EXAMPLE 2
Synthesis of the Reactive Dye RB 19
[0041] A mixture of 25 g RB 19, 2 g sodium hydroxide, and 500 g
distilled water is well stirred in a 1 liter round bottom flask for
10 minutes. After well dispersed, the temperature is raised to
40.degree. C. for one hour. Then 8 g HEMA and 0.02 g hydroquinone
are added to the above solution and well stirred. The solution is
reacted in an oil bath at 30.degree. C. for 24 hours. After cooled
to room temperature, the products are vacuum dried first and then
repeatedly purified with the methods such as extraction,
filtration, and drying as described in Example 1. The product after
this synthesis yields about 11 g dark powders. The result of HPLC
analysis indicates that the purified product has the purity almost
of 87%.
EXAMPLE 3
Synthesis of the Reactive Dye RB 21
[0042] A mixture of 25 g RB 21, 2 g sodium hydroxide, and 500 g
distilled water is well stirred in a 1 liter round bottom flask for
10 minutes. After well dispersed, the temperature is raised to
40.degree. C. for one hour. Then 8 g HEMA and 0.02 g hydroquinone
are added to the above solution and well stirred. The solution is
reacted in an oil bath at 30.degree. C. for 24 hours. After cooled
to room temperature, the products are repeatedly purified with the
methods such as extraction, filtration, and drying as described in
Example 1. The product after this synthesis yields about 10 g dark
powders. The result of HPLC analysis indicates that the purified
product has the purity near 90%.
EXAMPLE 4
Synthesis of the Reactive Yellow 15
[0043] A mixture of 25 g Reactive Yellow 15, 5 g sodium carbonate,
and 500 g distilled water is well stirred in a 1 liter round bottom
flask for 10 minutes. After well dispersed, the temperature is
raised to 40.degree. C. for one hour. Then 8 g HEMA and 0.02 g
hydroquinone are added to the above solution and well stirred. The
solution is reacted in an oil bath at 30.degree. C. for 24 hours.
After cooled to room temperature, the products are repeatedly
purified with the methods such as extraction, filtration, and
drying as described in Example 1. The product after this synthesis
yields about 8 g yellow powders. The result of HPLC analysis
indicates that the purified product has the purity near 92%.
EXAMPLE 5
Synthesis of the Reactive Red 180
[0044] A mixture of 25 g Reactive Red 180, 5 g sodium carbonate,
and 500 g distilled water is well stirred in a 1 liter round bottom
flask for 10 minutes. After well dispersed, the temperature is
raised to 40.degree. C. for one hour. Then 8 g HEMA and 0.02 g
hydroquinone are added to the above solution and well stirred. The
solution is reacted in an oil bath at 30.degree. C. for 24 hours.
After cooled to room temperature, the products are repeatedly
purified with the methods such as extraction, filtration, and
drying as described in Example 1. The product after this synthesis
yields about 7 g powders. The result of HPLC analysis indicates
that the purified product has the purity almost of 93%.
EXAMPLE 6
Preparation of the Tinted Soft Contact Lenses
[0045] The basic formulation prepared to make the soft contact
lenses is listed as followings: 100 parts HEMA, 15 parts N-vinyl
pyrrolidone, 0.2 part 2-chlorothioxanthone photo initiator), 1.5
parts ethylene glycol dimethacrylate (crosslinker), 1.2 part of
methacrylic acid, 0.04 part synthesized reactive tinting compound
(as prepared in Examples 1-5), and 100 parts glycerin diluent.
After well mixed in the ultrasonic bath and filtered, the mixture
is placed in the polystyrene mold with a diameter of 12.66 mm, a
base curve of 8.625, a central lens thickness of 110 microns, and
the power of 100,.and cured under a 250 watt UV lamp (wavelength
300-410 nm) for 15 minutes at 60.degree. C. The total accumulated
light energy is 1900 mJ/cm.sup.2. After curing, the lens is
demolded, rinsed with the 80.degree. C. hot water for 20 minutes to
remove the inert diluent and unreacted residual constituents, and
then hydrated with a standard saline at 25.degree. C. for 24
hours.
[0046] The UV-VIS spectra of the lenses are analyzed with a
Perkin-Elmer UV-VIS 8453 spectrophotometer before and after
autoclave aging. The lens is hold in a quartz cuvette filled with
saline. The UV-VIS spectra are obtained at 1 nm resolution from 190
to 1100 nm. The autoclave is operated at 121.degree. C. and 2 atm.
One cycle of autoclave takes about 30 minutes. The color fastness
of the tinted lens is assessed after three cycles of autoclave
aging. The test results are listed in Table 1.
[0047] The tensile properties of the lens are measured with using
an Instron at a strain rate of 50 mm/min. The specimen with the
desired size and shape is die-cut from the hydrated lens and the
cross sectional area of the specimen is measured. The tensile
strength and strain obtained are also shown in Table 1.
* * * * *